Turtles are among the most evolutionally successful animals on Earth. They have existed for approximately 200 million years. However, of the 250 or so species that exist today, many - both freshwater and marine - are now under threat.
The basic form of sea turtles has changed little over 100 million years. Australia is home to at least 36 described species of freshwater turtle, and six of the seven recognized marine turtle species. Many are also unique to Australia.
Populations of turtles are currently in decline as they compete with ever expanding human populations for water and resources.
Coastal development, economic development and a growing population have led to the urbanization of many parts of Australia’s coastline and developments on islands. All are threats to sea turtle survival. In areas near sea turtle rookeries, this has created several problems.
Feral animals: Feral pigs, foxes and dogs inhabit many coastal areas in Australia, sometimes adjacent to sea turtle rookeries. These introduced animals have good sight and a sharp sense of smell. They easily locate freshly-laid eggs which they dig up and eat.
Rubbish and pollution: Plastic and other discarded debris drifts on ocean currents. Unfortunately, sea turtles can mistake rubbish for food. Floating plastic bags look like jellyfish, a favourite food of loggerheads and leatherbacks. When sea turtles ingest plastic, their intestines become blocked and they starve to death.
Commercial trawl nets: Trawl nets are used to catch prawns and scallops in northern Australia.
Unfortunately, trawl nets also catch a wide variety and sometimes large quantities of unwanted species.
TED’s (turtle excluder devices) have been developed to reduce the capture of turtles and other large non-target species in commercial trawl nets. Turtle Excluder Devices are a modification to the trawl net that allow larger animals to escape after being taken into the net, as it is difficult to prevent or reduce the number of unwanted bycatch animals that enter the trawl net in the first instance. The mandatory use of TED’s is helping to prevent sea turtles from being caught in Australian trawl fisheries.
What is a TED? A “Turtle Excluder Device” is a grid of bars with an opening either at the top or the bottom of the trawl net. The grid is fitted into the neck of a shrimp trawl. Small animals such as shrimp pass through the bars and are caught in the bag end of the trawl.
When larger animals, such as marine turtles and sharks are captured in the trawl they strike the grid bars and are ejected through the opening.
Key findings of the 2007 State of the Environment Report in Queensland are that, in combination with fisheries closures, the introduction of turtle exclusive devices into trawl nets from 2001 has minimized the impact of trawling activities on sea turtles and the number of loggerhead turtles nesting has stabilized.
World Turtle day began in 2000 in Malibu in California. It has spread rapidly world-wide. The day is organised in Australia by Australian Marine Conservation Society and The Wilderness Society of WA who are calling for the federal government to establish a network of marine sanctuaries to protect turtles and other marine life.